Biofeedback Training to Increase P co2 in Asthma With Elevated Anxiety: A One-Stop Treatment of Both Conditions?

Abstract

Anxiety is highly prevalent in individuals with asthma. Asthma symptoms and medication can exacerbate anxiety, and vice versa. Unfortunately, treatments of comorbid anxiety and asthma are largely lacking. A problematic feature common to both conditions is hyperventilation. It adversely affects lung function and symptoms in asthma and anxiety. We examined whether a treatment to reduce hyperventilation, shown to improve asthma symptoms, also improves anxiety in asthma patients with high anxiety. One hundred twenty English- or Spanish-speaking adult patients with asthma were randomly assigned to either Capnometry-Assisted Respiratory Training (CART) to raise P co2 or feedback to slow respiratory rate (SLOW). Although anxiety was not an inclusion criterion, 21.7% met clinically relevant anxiety levels on the Hospital Anxiety and Depression Scale (HADS). Anxiety (HADS-A) and depression (HADS-D) scales, anxiety sensitivity (Anxiety Sensitivity Index [ASI]), and negative affect (Negative Affect Scale of the Positive Affect Negative Affect Schedule) were assessed at baseline, posttreatment, 1-month follow-up, and 6-month follow-up. In this secondary analysis, asthma patients with high baseline anxiety showed greater reductions in ASI and PANAS-N in CART than in SLOW ( p values ≤ .005, Cohen d values ≥ 0.58). Furthermore, at 6-month follow-up, these patients also had lower ASI, PANAS-N, and HADS-D in CART than in SLOW ( p values ≤ .012, Cohen d values ≥ 0.54). Patients with low baseline anxiety did not have differential outcomes in CART than in SLOW. For asthma patients with high anxiety, our brief training designed to raise P co2 resulted in significant and sustained reductions in anxiety sensitivity and negative affect compared with slow-breathing training. The findings lend support for P co2 as a potential physiological target for anxiety reduction in asthma. Clinicaltrials.gov Identifier: NCT00975273 .